A man was detained in Manchester, England, on New Year's Eve after three people were stabbed at the Manchester Victoria railway station, British Transport Police said.
A male British Transport Police officer, another man and a woman were taken to the hospital with knife injuries, Greater Manchester Police said.
"Tonight's events will have understandably worried people but I need to stress that the incident is not ongoing, a man is in custody and there is currently no intelligence to suggest there is any greater threat at this time," GMP Assistant Chief Constable Rob Potts said.
"While we don't yet know the full circumstances and are keeping an open mind, officers from Counter Terrorism Policing North West are leading on the investigation."
BBC producer Sam Clack happened to be at the scene. He heard the man "shout 'Allah' distinctly," but he didn't hear the rest of the sentence, he said on air with the BBC.
Shortly after the incident, Clack said this on Twitter:
"Just been very close to the most terrifying thing. Man stabbed in Manchester Victoria station on tram platform. Feet from me, I was close to jumping on the tracks as attacker had long kitchen knife. Totally shaken. This is seriously messed up."
The woman was injured in her face and abdomen and the man has injuries to his abdomen, GMP said. Both are in their 50s. The BTP officer was stabbed in the shoulder.
Their injuries are serious but not life-threatening, GMP said.
New Year's Eve fireworks at Albert Square went on as planned despite the incident, according to Manchester City Council.